Farmers, like others, seek to increase their productivity. As farm sizes increase more work must be done in the same period of time. For example, the planting season on a farm extends over a fixed period of days. To increase the area farmed, the farmer must plant crops on the increased area in the same planting season or reduce crop yield. As a result, there is a need for planting equipment capable of covering more area per day. One approach to increase productivity is to increase the width of the planting equipment. However, there are physical limitations regarding the size of the equipment. Another approach is to increase the operating speed of the planting equipment.
One common form of planter utilizes a vacuum disk seed meter for each row unit of the planter. One example of such is shown in U.S. Pat. No. 5,170,909. There, a seed disk is rotated past a pool of seeds on one side thereof. A plurality of seed cells formed by recesses in the surface of the seed disk at one or more circumferential rows of holes adjacent the outer periphery of the seed disk mechanically accelerate and eventually capture therein individual seeds from the seed pool. The individual seeds are held within the cells by a pressure differential created by a vacuum source coupled to the inside of the housing on the opposite side of the seed disk until the cells reach a discharge area. At the discharge area, the effects of the vacuum are cut off so as to release the individual seeds from the cells for discharge through a chute at the bottom of the housing to a seed furrow below. To increase the planting speed with such a disk, the disk must rotate faster, which may adversely impact seed pick-up and singulation, or the diameter of the disk must be increased to deliver an increased number of seeds while rotating at the same number of revolutions per minute. Increasing the diameter of the disk raises the height of the seed discharge area, allowing the seeds to ‘free fall’ a greater distance. This adversely impacts seed placement accuracy.
Conveyor belts have also been used in planter row units as shown in U.S. Pat. No. 6,681,706. There the belt is not used to meter the seed but to convey the seed from the meter to a drop point. Belts have been used in grain drills as metering devices as shown in U.S. Pat. No. 6,581,535. The belt is equipped with a number of recesses which collect the seed and move the seed to a drop location. Such a belt functions as a volumetric meter that does not singulate seed to provide individual seeds.